Sulfur Dioxide Problems in Wine
The application and addition of sulfur dioxide is challenging. If you make a mistake in an addition somewhere during your winemaking career, know you are not alone.
This Production Guide provides details regarding free sulfur dioxide (SO2) levels during immediate, pre-bottling stages. Specifically, it looks at pre-filtration (prior to plate-and-frame, lenticular, or crossflow filtration), in between rough/fine filtration and sterile filtration, and prior to bottling.
For some wines, a high free SO2 concentration may be experienced. At certain stages of production, having an elevated free SO2 is not necessarily a bad thing. For wineries that cannot eliminate headspace in tanks or use tanks that can integrate a fair amount of oxygen over time (e.g., variable capacity tanks or plastic tanks/totes), elevating the free SO2 above the 0.85 mg/L (molecular) target for that white or rosé wine may be a winemaking strategy to minimize microbial growth. (For red wines that do not have a high pH, the molecular target is usually 0.50 mg/L even though this is not an antimicrobial concentration. Refer to “Demystifying Sulfur Dioxide” and “Sulfur Dioxide Strategies for Juice and Wine” for more information on sulfur dioxide chemistry and use in wine.)
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